It has been proposed to substitute, for conventional mechanical door locks, systems of various sorts in which a physical or code-generated "key" is recognized by an electronic circuit which enables a locking bolt to be withdrawn. However, these types of electronic locks require a battery or other power source, such as a solar cell, to be incorporated in the lock housing. Failure to change the lock battery or inadequate ambient lighting makes it impossible to reliably operate conventional electronic locks.
Attempts have been made to utilize in-the-door power generation to eliminate the need for an external power source in electronic locks. PCT International Publication No. WO 80/02710 shows the use of an in-the-door electrical generator to power electronic decision makers to move bolts or gates which allow latches to be moved.
U. S. Pat. No. 4,433,355 to Chew et al. discloses an electronic lock for a door including a built-in generator for generating electrical energy to operate an electronic code recognition circuit. The generator is linked to a door handle spindle.
U. S. Pat. No. 4,912,460 to Chu discloses an electromechanical gating mechanism including electrical energy generating means which generates electrical energy in response to and utilizing energy derived from mechanical motion continuously generated by an individual pushing a key into a lock or operating a series of buttons or touch pad areas which produce energy piezoelectrically.